1. Field of the Invention
The present invention relates to a liquid crystal dispensing apparatus of a LCD (liquid crystal display), and more particularly, to an apparatus and a method for dispensing liquid crystal capable of dispensing small amounts of liquid crystal accurately.
2. Discussion of the Related Art
With the rapid development of the telematique field, importance of the display industry for displaying information is correspondingly growing. Up to now, among information displays, because a CRT (cathode ray tube) can display various colors and show good screen brightness, it has been favored. However, according to a need for a large, portable, high definitional display, it has been required to develop a flat panel display instead of a CRT which has heavy weight and large volume. The flat panel display has wide and various application fields such as in airplanes and spacecraft. At present, there are a LCD (liquid crystal display), an ELD (electroluminescent display), a FED (field emission display), and a PDP (plasma display panel), etc. as a flat panel display.
In the LCD, a sealant is printed onto a color filter substrate on which a color filter and a black matrix layer are formed. A spacer is scattered onto a thin film transistor substrate on which an electrode and a thin film transistor are formed to maintain a cell gap between the two substrates. The two substrates are adhered to each other, and liquid crystal is injected therebetween.
In general, the LCD includes a TFT substrate, a color filter substrate and a liquid crystal layer formed therebetween. Data lines and gate lines are arranged lengthwise and breadthwise onto the TFT substrate to define pixel regions. A TFT (thin film transistor) is arranged on a portion at which the data line and the gate line cross each other as a switching element, and a pixel electrode is arranged on the pixel region to be connected to the TFT. In the meantime, R, G, B color filter layers for displaying colors are arranged onto the color filter substrate, and a black matrix layer is arranged to prevent light from being transmitted to the TFT, (the data line and the gate line.) An ITO (indium tin oxide) layer is arranged onto a whole surface including the black matrix layer and the color filter layer.
In the liquid crystal display apparatus, various patterns are formed onto the TFT substrate and the color filter layer, the two substrates are adhered to each other, and liquid crystal is injected. Herein, there are many methods for injecting liquid crystal. Among them, a vacuum injection is largely used where an internal space of the cells is vacuumed and liquid crystal is drawn into the cells using a pressure difference is largely used.
In more detail, the liquid crystal injection using the pressure difference after maintaining the cells at a vacuum state is performed in a vacuum chamber. First, the liquid crystal panel having the two substrates adhered with each other are arranged in the vacuum chamber. Air pressure is gradually reduced so that the internal space of the liquid crystal panel is in a low pressure state—almost a vacuum state. When the internal space of the liquid crystal panel is in the low pressure state, an injection opening is contacted to liquid crystal. Then, air is injected into the chamber so that the pressure outside the liquid crystal panel is gradually increased. Thus, a pressure difference occurs between the inside and outside of the liquid crystal panel, and accordingly, liquid crystal is injected into the liquid crystal panel.
However, in the above-described liquid crystal injection method, a significant amount of time is required to inject liquid crystal into the liquid crystal panel. In addition, staining may occur at the injection opening. Consequently, lower picture quality and loss lots of liquid crystal result.